Plasma Sheath Thickness via Phase Adjustment
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Solution Overview
Problem
Conventional plasma processing methods struggle to significantly reduce the number of particles adhering to substrates during plasma treatment due to limitations in increasing the sheath thickness between the plasma and the substrate, as power reduction alone does not effectively enhance sheath thickness.
Innovation Solution
A plasma processing method that adjusts the phase of the voltage of the lower electrode relative to the upper electrode using a phase adjustment circuit, increasing the potential difference without altering plasma density, thereby significantly increasing the sheath thickness and effectively separating particles from the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If power is reduced to increase sheath thickness, then the sheath thickness increases slightly, but the increase is not significant enough to effectively reduce particle adhesion
Solution Approach 1:
The patent changes the phase parameter of the voltage applied to the lower electrode relative to the upper electrode. By adjusting this phase difference, the potential distribution in the plasma is modified, which significantly increases the sheath thickness without requiring substantial power reduction. This phase parameter change enables effective particle separation while maintaining plasma generation efficiency.
Solution Approach 2:
The patent dynamically adjusts the phase of the voltage during the plasma processing. The phase adjustment circuit modifies the voltage phase in real-time to optimize sheath thickness during different stages of the process. This dynamic control allows the system to achieve maximum particle separation effectiveness while maintaining plasma stability and avoiding excessive power consumption.
2Object-affected harmful factors
If high-frequency power is reduced to change sheath shape, then particles are separated from the substrate, but the power reduction alone cannot significantly increase sheath thickness
Solution Approach 1:
Instead of only reducing power to change sheath characteristics, the patent introduces phase adjustment as an additional control parameter. By changing the phase relationship between the voltages on the upper and lower electrodes, the sheath thickness is significantly increased without requiring substantial power reduction. This enables effective particle separation while maintaining higher plasma power for efficient processing.
Solution Approach 2:
The patent applies phase adjustment as a preliminary action before or during the plasma treatment to pre-establish an optimal sheath thickness. This preliminary phase adjustment ensures that when plasma treatment occurs, the sheath is already configured to effectively separate particles from the substrate, preventing particle adhesion before it becomes a problem rather than attempting to correct it after the fact.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for a substantial increase in sheath thickness, leading to a significant reduction in particles adhering to the substrate, with particles being moved further away from the substrate and discharged, thereby improving the cleanliness of the plasma-processed surface.
Implementation Method 1
a phase adjustment circuit configured to relatively adjust a phase of a voltage of the lower electrode with respect to a phase of a voltage of the upper electrode
Implementation Method 2
increase a thickness of a sheath between the support stage and the plasma
Implementation Method 3
a high-frequency power supply configured to supply a high-frequency power so as to generate plasma in the internal space
Implementation Method 4
the gas is supplied from the gas supply to the internal space, and the high-frequency power is supplied from the high-frequency power supply so as to excite the gas to generate plasma
Implementation Method 5
a process of discharging gases and particles in the internal space using the exhaust device
Data Source
AI summary
A plasma processing method according to an embodiment is performed in a state in which a substrate is placed on a support stage in an internal space of a chamber body. In the plasma processing method, a plasma treatment is performed on the substrate. Subsequently, a phase of a voltage of a lower electrode is relatively adjusted with respect to a phase of a voltage of an upper electrode by a phase adjustment circuit, such that a thickness of a sheath between the support stage and plasma without extinguishing the plasma generated in order to perform the plasma treatment. Thereafter, in a state in which supply of a high-frequency power is stopped, gases and particles in the internal space of the chamber body are discharged using an exhaust device.